Mass storage systems continue to provide increased storage capacities to satisfy user demands. Photo and movie storage, and photo and movie sharing are examples of applications that fuel the growth in demand for larger and larger storage systems. A solution to these increasing demands is the use of redundant arrays of multiple inexpensive disks (RAID).
Multiple disk drive components may be combined into logical units. Data may then be distributed across the drives in one of several ways. RAID is an umbrella term for computer storage schemes that can divide and replicate data among multiple physical drives. The physical drives are considered to be in groups of drives, or disks. Typically the array can be accessed by an operating system, or controller, as a single drive.
In disk groups, typically, all virtual disks configured on other disk groups are moved to write-through mode when a reconstruction or on-line capacity expansion is in progress. All disk groups use DRAM resources during Reconstruction or On-line Capacity Expansion . During such operations, every Virtual Disk configured on the Controller is invariably moved to write-through mode.